1. Field of the Invention
The present invention relates to an apparatus and a method which is capable of reducing a required time for switching a channel of a television, in particular to a channel control apparatus of a digital television and a method thereof which is capable of outputting a video and an audio signal corresponding to a user select channel by storing PIDs (Packet Identifier) of the video and audio signal of the channel and extracting the stored PIDs (Packet Identifier) in accordance with a channel switching request of the user.
2. Description of the Prior Art
FIG. 1 is a block diagram illustrating the conventional channel control apparatus of a digital television. Its operation will now be described.
First, a tuner 2 receives a VSB (Vestiginal Sideband) or a QAM (Quadrature Amplitude Modulation) signal from an antenna and wave-detects it, corrects an error, converts it into a transport stream format, outputs it to a transport packet parser 3. The transport packet parser 3 is inputted the transport stream, and outputs a de-multiplexed video signal, an audio signal, and additional information.
Herein, the de-multiplexing means dividing detected packet identifiers into a video signal line, an audio signal line, and additional information line. In addition, the packet identifier provides a de-multiplexing mean for de-multiplexing a timely multiplexed signal. In other words, the video signal packet, audio signal packet, and additional information (SI) packet can be identified by detecting the packet identifiers.
After that, ah audio decoder 4 is inputted the de-multiplexed audio signal, converts it into a decoded signal, and outputs it to a DC/AC converter 5. The DC/AC converter 5 converts the decoded audio signal into an analog audio signal, and outputs it to a speaker.
A video decoder 6 is inputted the de-multiplexed video signal, converts it into a decoded signal, and outputs it into a switching unit 7.
After that, a user interface 9 outputs an operation signal corresponding to a user select channel to a microcomputer 10. The microcomputer is inputted the operation signal, and outputs a control signal in order to select a broadcasting signal of the channel selected by the user. In addition, the microcomputer 10 is inputted the additional information from the transport packet parser 3, processes it, and outputs it to a memory 11. The memory 11 stores the additional information according to the control signal.
An on screen display extracts on screen information corresponding to the operation signal from the memory 11, and outputs an on screen display video signal.
A switching unit 7 is inputted the decoded video signal and on screen display video signal from the video decoder 6, and performs a switching operation in order to output the decoding video signal and on screen display video signal selectively in accordance with the control signal.
A NTSC encoder (National Television System Committee Encoder) 8 is selectively inputted a signal outputted from the switching unit 7 in order to display the video signal on a CRT, and outputs a luminance signal and a chrominance signal.
FIG. 2 is a flow chart illustrating the conventional channel control method of the digital television. It will now be described in detail.
First, it is judged whether the user selects a request channel by using a channel transfer key S1.
In the result of the judging step, when the user selects the request channel, an audio signal and a video signal are stopped temporarily S2
When the audio signal and video signal are stopped for a time, a phase-locked loop data value is set on the tuner in order to switch the channel to the user request channel S3.
After parsing a PAT (Program Association Table)/PMT (Program Map Table) or a TVCT (Terrestrial Virtual channel Table), the packet identifiers of the audio and video signal of the user request channel are extracted, and the selected packet identifiers are set on the transport packet parser 3.
After setting the selected PIDs, when the video and audio signal are decoded on the decoder through the set PIDs, the video and audio signal stopped temporarily are released S5.
However, in the conventional channel control apparatus for the digital television and the method thereof, when the user requests a channel, a time for switching the channel of the digital television is required a lot because the conventional technology performs parsing of the PAT (Program Association Table)/PMT (Program Map Table) or TVCT (Terrestrial virtual Channel Table).
For example, in switching from the present channel to the other channel, the user has to spend a lot of time to watch the other picture from the present picture because of the time required for the parsing.
The object of the present invention is to provide a channel control apparatus of a digital television and a method thereof which is capable of performing selectively parsing of a PAT (Program Association Table)/PMT (Program Map Table), or a TVCT (Terrestrial virtual channel Table) in order to switch to a user select channel promptly.
In order to achieve above-mentioned object, the channel control apparatus of the digital television for outputting a user request video and audio by controlling a channel of the digital television comprises a transport packet parser for extracting a packet identifier of a video, audio and additional information of a user select channel, a microcomputer for storing the extracted packet identifiers on a memory, and setting the stored packet identifiers on the transport packet parser, and a decoder for decoding the video and audio signal after receiving the signals through the set packet identifiers.
In addition, the channel control method of the digital television comprises a judging process for judging whether the packet identifiers of the video and audio signal corresponding to the user select channel are stored on the memory when the user selects a request channel, a setting process for setting the stored packet identifiers of the video and audio signal on the transport packet parser when the packet identifiers of the video and audio signal are stored on the memory, and a decoding process for decoding the video and audio signal after being inputted the video and audio signal corresponding to the user select channel through the set packet identifiers of the video and audio signal.